A microcolumn has been initially introduced in the 1980s as an electron beam microcolumn based on an electron emitter and an electronic optical element of a microstructure which operate under the basic principle of a scanning tunneling microscope (STM). The electron beam microcolumn forms an improved column by delicately assembling fine elements to minimize an optical numerical value.
The microcolumn generally includes an electron emitter, a source lens, an Einzel lens, and a deflector. With regard to the microcolumn, the structure of a single microcolumn is disclosed in Korean Patent Application No. 2003-66003 as an example. Related papers include “An electron beam microcolumn with improved resolution, beam current, and stability” by E. Kratschmer et al. 6, J. Vac. Sci. Technol. B13(6), pp. 2498-2503, 1995, and “Experimental evaluation of a 20×20 mm footprint microcolumn” J. Vac. Sci. Technol. B14(6), pp. 3792-3796, 1996. Related patents include U.S. Pat. Nos. 6,297,584, 6,281,508, and 6,195,214. A multi-microcolumn may be composed of a single column module (SCM) where a plurality of single microcolumns are arranged in series or parallel, or two or more standardized monolithic column modules (MCMs), i.e, a multi-column adopting 2×1 or 2×2 as a set. Further, there is a multi-column structure composed of a wafer-scale column module (WCM) where a piece of wafer acts as a lens element of a column. This basic concept is disclosed in a paper “Electron beam microcolumns for lithography and related applications” by T. H. P. Chang et al. 8, J. Vac. Sci. Technol. B14, pp. 3774-3781, 1996. Another mode is a hybrid multi mode in which one or more columns may be arranged together with SCM and MCM or WCM, and some lens elements of the column may employ SCM, MCM, or WCM. Basic experimental results of this are disclosed in papers “Multi-beam microcolumns based on arrayed SCM and WCM” by Ho-Seob KIM et al. 7 persons, Journal of the Korean Physical Society, Vol. 45, No. 5, pp. 1214-1217, 2004, Microelectronic Engineering by Ho-Seob KIM et al. 6, pp. 78-79, pp. 55-61, 2005, and “Arrayed microcolumn operation with a wafer-scale Einzel Lens”.
The conventional electron microscope is very large in size. Thus, when being observed by the electron microscope, a sample should be carried to a place such as a research institute where the electron microscope exists. This is inconvenient in the temporal and spatial aspect.